Osteosynthesis operations are practised at the present time with the help of rigid elements which are associated with the fractured bone in order to reinforce it and to restore as quickly as possible to the patient his faculties of movement. These reinforcing elements are formed for instance by plates fixed to the outer surface of the bone on either side of the fracture or by hollow pins or broaches which are inserted in the medullary canal of the bone. The latter elements are employed more and more often since they are the least traumatizing for the patient and enable a rigidification of the fractured bone, the broach resisting not only compressive and tensile forces, but also torsional forces. It is this latter property of the broaches which may be obtained only if they are fixed not only longitudinally, but also in rotation about their axis, particularly in certain types of fractures called "low" or "high" (diaphyso-epiphyseric fractures). Consequently, if the broach must resist twisting, it is necessary to place transversal screws which pass diametrically through the bone as well as one or several pairs of aligned holes usually provided close to the distal end of the broach. This practise is above all applied in cases where the fractured bone is the femur or tibia.
The broaches are of themselves known. They generally exhibit a cross-section having a form approximately trefoiled, one of the ends being slightly splayed and provided with interior threading, the other end being slightly tapered in order to facilitate insertion into the medullary canal. Moreover, according to the type of application, the broach may be somewhat curved along its longitudinal axis and exhibit longitudinally a slot over its entire length, which gives it a certain flexibility in bending, this permitting at the time of insertion a perfect adaptation to the form of the medullary canal. As is well understood, the surgeon has available a choice among various lengths and diameters which are determined by the bone to be treated and the dimensions of the limb of the patient.
According to the present day technique, the surgeon initially puts the broach in place according to a known procedure, then proceeds to locate the transversal holes found at the distal end of the broach. To this effect he has available a locating apparatus employing X-rays by means of which he may indicate on the skin of the limb the place where the axis of the holes traverses the skin, then after having made an incision he pierces a hole by the aid of a drill passing via the holes of the broach. Thereafter, the screw may be fixed in place.
This process accordingly necessitates working with X-rays to which are exposed the patient as well as the operating room personnel. The locating operation requires approximately two hours and one must count on an exposure of approximately 400 to 1000 REM per operation. This important dose, to which is exposed the personnel each time that an operation is carried out, presently leads to hesitation among surgeons for the employment of this method, such surgeons preferring either to utilize plates or broaches not having transversal screws for reinforcement purposes.
The prolonged duration of the employment of the apparatus in the course of an operation naturally prevents its use for operations which might otherwise be realized at the same time in an operating room of the hospital other than that in which the operation under consideration takes place. This requires a very close programming of operations which is undesirable, particularly if there are emergencies.
The invention thus has as its purpose to provide an apparatus for marking it easier to locate in situ transversal holes in a hollow broach implanted in the medullary canal for the retention of the fragments of a fractured bone. More precisely, the invention provides an apparatus for rapidly positioning a drilling guide parallel to the axis of the transversal holes. The compensation of the distance between the axis of the drilling guide and the axis of a hole may thereafter be done quickly by conventional means.